The European Parliament’s Brexit co-ordinator insisted Britain should be treated as any other third country would be despite both sides striving to remain “as close as possible” after the split.

In his letter the Conference of Committee Chairs, Mr Verhofstadt reaffirmed his commitment to the negotiating deadlines set by the European Council in March.

They state the “UK should be subject to the relevant conditions for the participation of third countries to be established in the corresponding programmes”.

Non-EU members are allowed to participate in a number of the bloc’s schemes, such as its research and innovation arm Horizon 2020 – which even Canada participates in.

In the memo seen by Express.co.uk, Mr Verhofstadt said: “I write to raise with you, as I briefly did at the CCC meeting, a number of issues in relation to provisions governing third country participation, as applicable, to the next generation of MFF programmes.”

He adds: “It is clear that no specific treatment should be granted to the UK, as compared to other third countries, as regards its possible participation to the future generation of MFF programmes.

“It also follows from the above that, as any third country, the UK should play no role in the governance and decision-making of the programmes and that the financial provisions should ensure that there is no significant net return from the EU budget to any third country.”

The former Belgian prime minister’s letter, which is dated September 26, suggests to the EU Parliament’s committees that they take heed of his advice when working on the bloc’s budget for 2021-2027.

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He also recognises the potential damage to EU programmes caused by Britain’s departure but maintains his opposition to any future compromises on participation being made.

“As repeatedly stated by Parliament, a third country cannot have the same benefits and level of access to EU programmes as a member state and is it therefore clear that the UK becoming a third country will have an impact in certain policy fields where the UK is now particularly active,” he says.

“The future relationship with the UK should be based on a balance of rights and obligations and should not put into question the EU’s current relationships with other third country partners.”

Ukip deputy leader Mike Hookem accused Mr Verhofstadt and the EU of wanting to "fleece the UK for every penny".

Responding to the letter, the British MEP said: "If anyone wanted further evidence that the EU is determined to fleece the UK for every penny, while trying to punish us for having the audacity to leave the EU club, then this is it.

"While Verhofstadt drones on about third-country status, he seems to forget that the UK has spent over 40 years contributing to the EU budget; have a share in every asset the EU owns and will be paying the ridiculous £40billion divorce bill for many years to come."

While not playing an official part in the EU’s Brexit negotiations, Mr Verhofstadt, as chair of the Parliament’s Brexit Steering Group, has held a number of high-level talks to ensure a deal acceptable to MEPs is reached.

The influential MEP recently held negotiations with Prime Minister Theresa May at Downing Street and invited Irish leader Leo Varadkar to discuss the thorny border conundrum while he was in Brussels last week.

Mr Verhofstadt will, however, be absent when EU heads of state gather in Brussels for the European Council summit next week.

The crunch meeting will feature a Brexit dinner where Mrs May will likely brief her counterparts on the UK’s new Irish backstop proposal before leaving the room to allow an EU27 debate on the divorce.

EU negotiator Michel Barnier said “decisive progress” must be made ahead of the October 17-18 summit if both sides are to conclude a timely withdrawal agreement.